QD package is written by by Yozo Hida, Xiaoye S. Li, David H. Bailey and others in LBNL.
This libqd is a port the QD for windows. It will be added enhancement and improvement to the original QD package on this repository. This package supports both a double-double datatype (approx. 32 decimal digits) and a quad-double datatype (approx. 64 decimal digits). The computational library is written in C++. C++ high-level language interfaces are provided to permit one to use convert an existing C++ program to use the library with only minor changes to the source code.

Omitted C language support.
Specified for Windows.

I reported some bugs which I found when I tested with improvement plan. Part of the proposition was merged officaly.
qd-2.3.16: sincosh and tanh problems
qd-2.3.17: nroot problem

LBNL High-Precision Software Directory (http://crd-legacy.lbl.gov/~dhbailey/mpdist/)
My old repository on google code (https://code.google.com/archive/p/libqd/)